This invention relates to a panel fastener, and more particularly to an aircraft panel fastener with a holdout for holding the fastener in a retracted position when the fastener is disengaged from its nut member on the aircraft.
Panel fasteners for securing aircraft panels are well known in the art. The fastener, of the type this invention is concerned with, comprises a stud-like body with an enlarged head and secures a panel to an aircraft structure by being inserted through an opening in the panel and then engaged with a nut member attached to the aircraft structure. Typically the fastener is also captivated to the panel by a retaining ring which retains the fastener on the panel when the fastener is disengaged from the nut member.
To prevent the fastener from becoming damaged when the panel is removed and, for example, slid on a flat hard surface, on interfering with the positioning of the panel on the aircraft preparatory to fastening the panel, it is desireable in these instances that the fastener be held in a retracted position. In this position, the fastener extends outwardly to the maximum extent permitted by the retaining ring and the lower end of the fastener is substantially within the panel. The retention is usually accomplished by some type of spring holdout which is carried on the fastener and bears against the wall of the panel opening when the fastener is retracted, thereby holding the fastener. After the panel is positioned on the aircraft for installation, the fastener is depressed downwardly against the spring tension of the holdout to engage the nut member and thereby secure the panel.
A common problem associated with known holdouts is that sealant, ordinarily inserted between the panel and the aircraft structure, or other such debris, comes in contract with the spring member and piles up or packs in behind and around it causing it to stick or otherwise become inoperative. Another problem is that the spring member constituting the holdout is usually permanently installed on the fastener body and cannot be removed or replaced without special tools and equipment, if at all. Permanent installation of the spring member not only results in an additional cost of manufacture, but also prevents the holdout from being quickly replaced when damaged. Also, with the holdout permanently installed, the fastener cannot be easily overhauled. Periodic overhaul of the fastener is required in many instances to recoat the fastener with an anti-corrosive material.